The Lymphoma-Leukemia Program is a unified multi-disciplinary study of malignant lymphomas and related leukemias and immunoproliferative disorders that has as its goal the definition of their cellular and clinical characteristics in terms of modern understanding of immunology including the T and B lymphocytic systems and alterations of lymphocyte transformation. It combines a multiparameter approach employing a variety of immunologic surface marker technics with cytochemistry, ultrastructural, in vitro and immunoglobulin detecting techniques for the cellular definition with the in-depth Hodgkin's staging techniques for the defining of clinical expressions. The results of the initial definitional phase during the first two years have demonstrated the effectiveness of this multiparameter definitional approach for characterizing human lymphoid neoplasms according to the T and B cell systems and relating these neoplasms to abnormalities of lymphocyte transformation and to the functional lymphoma classification of Lukes & Collins. A Southern California Lymphoma Group involving 16 major area hospitals also has been developed, as part of the regional collaboration to enhance the collection of fresh lymphoma case material for study. It also extends to the community the morphologic, technical, and clinical expertise that influences the quality of patient care. This program interrelates with regional epidemiologic and Cancer Control Programs. In the renewal phase of the program the definitional phase will be continued and new in-depth areas of investigation that have evolved out of the initial phase will be extended into following new areas: (1) Control mechanisms of lymphocytes transformation as related to lymphomas; (2) Immunoglobulin characterization and synthesis; (3) Visualization of membrane and cytoplasmic antigens by the immunoperoxidase technique; (4) Cell kinetics; and (5) Exploratory Data Analysis.